Homemade backhoe advice

You can do anything, but it will cost you a lot more than a real backhoe and it will likely not be very usable.

Exactly.

The little towable backhoes and tractor attachment backhoes sort of work, but they are painfully slow, often can only actuate one joint at a time and have very little diging power. They have open center hydraulics with gear pumps of perhaps 10gpm and rarely have more than 20hp driving them.

By contrast a "real" backhoe has 75-100hp or more driving a high flow variable displacement piston pump with 30 or more gpm for closed center hydraulics. Ripping forces are 10,000#+, lift at full extension is a couple thousand pounds or more, you can operate all four joints at once in a coordinated fashion and move any joint through it's full travel in a couple seconds at most.

Buy a used "real" backhoe and refurbish it if you want to do any actual work with it.

"Dan waltz" wrote in message news:c2351$5475547a$43de0cc0$ snipped-for-privacy@news.flashnewsgroups.com...

I built a bucket loader for my garden tractor that performed as designed, inexpensively from mostly used and rebuilt hydraulics. Here in New England there is snow to plow and a fair amount of excavation for construction, so the hydraulics business is thriving. Three local shops helped me with rebuilding and two stores contributed the fittings. The hoses came from Northern Tool, at a small fraction of the cost of custom ones.

The design sequence was to roughly estimate what I needed and then guess on the spot if cheap used components could be repaired and shoehorned into it. The cylinders are single-acting Porta-Power units with short strokes that required some geometric gymnastics to leverage the longer throws I needed. I magically found two 4-ton and two 10-ton ones in a discount tool store that doesn't normally have used stuff, for $15 and $20 each. All needed new seals that a nearby shop ordered for me. The seals were correct only on OD and I had to machine bushings to adapt them to the pistons. I can see why shops tell me Chinese cylinders aren't repairable.

Once I had a set of hydraulics I advanced the mechanical design geometrically, graphically and with a wood mockup to check angles and clearances, especially for assembly tools and the bulky grease gun.

There's no way I could have done it without a metal lathe and milling machine. The biggest difficulty was drilling sufficiently parallel bearing holes in both ends of components longer than my milling machine's table travel.

Doing it once was a "learning experience."

It would probably have been very expensive to buy hydraulics to fit an existing mechanical design. While I was in the store a plow operator came in needing a custom hose similar to one I had paid about $12 for. He paid $120. Similarly if I hadn't been free to make changes the pump would have cost $300 instead of $80, and the valve $150 instead of $40.

I suggest that you thoroughly analyze the maximum forces on all parts of the backhoe before you modify it. I had to push bearing pressures beyond the recommendation for Oilite, and made the sleeves from brass water pipe. I used the moment to lift the back wheels off the ground as the maximum static load, and just guessed at the max dynamic load from hitting an obstacle. Actually the front tire sidewalls sprung leaks before the back came up. Wood crush blocks have prevented serious collision damage in use. I had to straighten the bucket and replace one slightly bent pivot pin.

-jsw

Several youtube videos showing them in use:

I think you would be hard pressed to build one less expensively than what Harbor Freight will sell you one. Unless you already have a bunch of the parts...